Associated PressA little brown bat with white-nose syndrome in a cave in Stockbridge, Vt.
A “biodiversity crisis”: that’s how some conservationists describe new numbers released this week by the federal Fish and Wildlife Service on so-called white-nose syndrome. According to the agency, 5.7 million to 6.7 million bats have died from the fungal ailment in eastern North America since an epidemic first broke out in upstate New York in 2006.
The new numbers are striking, and far higher than the previous bat mortality estimate of one million released in 2009, yet it is hard to put the number into perspective because researchers lack baseline data for many bat species populations from before the disease started demolishing colonies.
“We knew numbers for endangered species like the Indiana bat,” said Ann Froschauer, who coordinates communications releases on the bat disease for the Fish and Wildlife Service. “But we never made it a priority to count something like little brown bats, because, well, they were everywhere. It didn’t seem possible that they would be in danger of extinction in just a couple years.”
What is known is that when the fungus gets into a cave or mine where bats are hibernating, 70 to 90 percent of the bats die. In some cases, the mortality rate is 100 percent.
Over the past three years, the disease has spread from 88 sites in nine states in 2009 to at least 200 sites in 16 states today. Jeremy Coleman, the lead white-nose syndrome coordinator
for the Fish and Wildlife Service, said that officials can’t keep up with new site infections and are now working on the assumption that all caves and mines are infected in areas where the ailment has existed
for several years.
There are 45 species of bats in North America, 26 of which are hibernating species potentially susceptible to the fungus. While the disease has infected only six species so far, some researchers worry that it could wipe out as many as 20 bat species in the next few years.
Molly Matteson, a conservationist for the Center for Biological Diversity, an environmental group, says that’s a big deal — not just for the environment but for people as well. Researchers have estimated that bats save farmers at least $3.7 billion a year by keeping down crop pests.
Ms. Froschauer emphasized that each bat species fulfills a specific ecological purpose. “I think people tend to put bats in a bucket and think of them as one species,” she said. “But they are a hugely diverse group of mammals, and each species has a very special ecological niche that can’t be filled by a different bat species.”
“Different species eat different things, hunt in different locations and fit into the ecological puzzle in a unique way,” she said. “Losing one bat species would be huge — losing 20 would be catastrophic.”
Some conservationists take a bit of hope from recent reports that resistance to the fungus is growing in the bat population in parts of the Northeast.
“I’d love to believe that,” said Dr. Coleman of the Fish and Wildlife Service. “I hate always being the guy with the bad news.”
“But just because some bats are surviving doesn’t mean that we will have viable populations in the future,” he said. “These new numbers make it quite clear that this is still a crisis and a growing one.”